<form method="get" id="searchform" action="<?php bloginfo('home'); ?>/">
<?php if (strlen(get_search_query()) > 0) { ?>
	<input type="text" value="<?php the_search_query(); ?>" name="s" id="s" />
<?php } else { ?>
	<input type="text" onfocus="if (this.value == 'Search') {this.value = '';}" onblur="if (this.value == '') {this.value = 'Search';}" value="Search" name="s" id="s" />
<?php } ?>

</form>